Henry Cavill's moustache is so famous it has made headlines around the world. So it comes as something of a disappointment that his top lip is perfectly smooth when we meet.

"Before you sit down, would you mind taking a selfie with me?" he asks, incredibly politely. "Is that all right?"

After he snaps the picture I inspect it for any inkling of a tache that ended up costing a film studio millions of dollars. Not a whisker.

For those who don't remember, Cavill was filming his part as a mustachioed August Walker in Mission: Impossible - Fallout when he had to return to the set of Justice League for some Superman re-shoots.

Cavill couldn't shave the facial hair off and Superman is moustache-free so Warner Brothers had to pay an eye-watering amount of money to CGI it out of the finished film.

"When they came to me to say they wanted me to shave it off, I got it, because Superman doesn't have a moustache," he explains.

"But I was about to go sit in a helicopter in New Zealand with my head out the window. A fake one just wasn't going to stay on there and so it was completely out of our hands. It was just bad timing. Really, really bad timing. What made it worse was that we then went on hiatus shortly afterwards anyway."

He chuckles mischievously. "I shouldn't laugh, but it's one of those things where life just likes to just punch you in the kidneys.

"I did kind of miss it when it was gone. When it came to shaving it off, I thought, 'Ah, this has created so much trouble that to shave it off seems a shame'."

The hiatus he is referring to came when Tom Cruise, who reprises his role as Ethan Hunt for a sixth outing and who famously does his own stunts, broke his ankle while leaping between buildings.

The megastar was filming on the streets of London when he slammed into a wall and broke the bone, forcing the production to halt until he could walk again.

"I was there," Cavill says. "I saw it and it looked like a hard hit at first, but because he just pulled himself up and kept on doing it I thought he had sprained his ankle.

"Then everything shut down and we were told the doctors were seeing Tom, but I thought that just meant the shot I was doing would be delayed and I would just chill out in the sun for a bit.

"But then we heard it was broken. Tom is a tough cookie - you're not worried for Tom in that situation, he's hard as nails - but what does this mean for our movie?

"In the end it just meant that we all got a break. We were all exhausted at that stage and I think a break was quite welcome.

"It meant we could perfect everything as we were going along, and we came back stronger." Indeed Cavill (35) learned a whole new set of skills to play mysterious CIA agent August Walker, skills that even Superman doesn't have.

"There is inevitably a shirtless scene in a Superman movie, so I will go from training very hard in the gym to a leaning process and that means eating a lot less.

"But when you're eating a lot less, and you're working the long hours which you usually work, it just becomes a bit of a hardship.

"On this one I didn't have to do that, but instead I did a lot of fight choreography, and it is far more complex in these movies because you don't break it up into super-powered moves.

"It was just months and months, including days off and weekends, learning stunt skills."

So it's a bit of a disappointment to Cavill that all of those hard-earned skills are next to useless.

"The problem with fight choreography is it's not useful in a real-life situation.

"It would look pretty good, but you're not going to hurt anyone with it."

Far more helpful is the motorbike licence he got while they were filming, inspired by seeing Cruise in action riding without a helmet in a lengthy chase sequence through the streets of Paris.

"I'm not looking back now. Next is going to be a helicopter licence," he promises.

It appears Cruise has been a significant inspiration for Cavill, in more ways than one, and he appears to be delighted when the megastar pops his head round the door of the hotel room to say hello.

That certainly made it easier for him on set, where he was a new addition to a tight-knit cast which includes Simon Pegg, Alec Baldwin, Rebecca Ferguson and Ving Rhames, all of whom had already been together for multiple movies.

"From what I remember, being a new boy at school, it was horrible, but this was actually a really good experience of being a new boy," Cavill says.

"They are like a family, very friendly, kind, welcoming and a very collaborative set.

"Everyone was all about talking through scenes and discussing stuff and there were no closed doors on set.

"It was always, 'If you have a question, ask, and we are going to talk you through it'."

His new-found ambition of getting his helicopter licence stems from another of the film's high-octane stunts - the one which prevented him shaving off his moustache and which sees Cruise pilot a chopper over the mountains of New Zealand as he chases another helicopter carrying Cavill.

"Tom did an amazing job. I'm not easily impressed - I know some people who are genuinely impressive and have done some mad, mad stuff, but Tom flying a helicopter in the mountains, I don't know anyone else who can do that."